What is Blastocyst?
The blastocyst is a stage in the early development of mammals and humans. It consists of an outer layer of cells trophoectoderm and an inner cell mass. The outer layer contributes to the formation of placenta and the inner cell mass gives rise to the body of the embryo.
Normally the embryos formed in the laboratory are transferred to the uterus on day three, for implantation and further development. In some cases, the embryos have to be cultured up to day five-six.